• Journal of Chest Surgery
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• 제22권3호
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• pp.416-424
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• 1989

We have performed eight, single transplantations of right lung in dogs from September, 1988 to March 1989 at the Thoracic & Cardiovascular Surgical department, Yonsei University, College of Medicine, Seoul, Korea. We wrapped bronchial anastomosis site with great omentum and used cyclosporin in preoperative and postoperative periods in seven cases except one. The one without wrapping the bronchial anastomotic site with omentum and using cyclosporin died due to bronchial anastomotic site rupture in postoperative fourth day. If there is no reason to choose one side over the other, we would generally choose to do left-sided transplant as this is technically somewhat easier because of the long length of recipient bronchus and the ease of clamping the left atrium proximal to the pulmonary veins. The right atrium limits the amount of left atrium that can have incorporated into the clamp proximal to the pulmonary veins on the right side. But we had chosen to do right-sided transplant of lung because we must take variable technical experiences on right sided lung transplant in dogs. We have to anastomose one of pulmonary vein and left atrial wall on right-sided transplant easily only with double ligation of one pulmonary vein because right atrium limited the clamp of left atrium proximal to pulmonary veins with decreased venous return and cardiac output in some dogs. All seven dogs with right-sided lung transplant had survived more than one day with good condition except one. The one dog have to be sacrificed to evaluate the difference between the gas analysis in pulmonary venous and arterial blood in post-operative eight hours. We found hemorrhagic pulmonary edematous changes of contralateral left lung in this dog. And also all dogs have to be sacrificed for the evaluation of surgical problems, anytime in post-operative periods without any cardiopulmonary resuscitative efforts when the general condition would be worse progressively. We found no any surgical technical errors in seven dogs except one with thrombi in suture site of left atrium. There were hemorrhagic pulmonary edematous changes of transplanted right lung in one, of contralateral left lung in one, of contralateral left lung with double ligation of its pulmonary artery in one, thrombi around left atrial sutures sites in one, multiple air leakage in one bronchial rupture in one due to rejection or infection. There were accidental extubation and delayed intubation in one and unknown cause of death in one.

• Tunnel and Underground Space
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• 제20권6호
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• pp.446-454
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• 2010

CAES-G/T (Compressed Air Energy Storage - Gas Turbine) power generation is a likely option for the buffer facility stabilizing the fluctuation of the renewable powers, such as wind and solar powers. Considering the geological conditions, the underground CAES facility is most probable if the CAES-G/T generation is planed in Korea. In this kind of facility, a concrete plug is installed to seal the compressed air in the container, so that the selection of the shape and dimension of concrete plug could be a critical design factor. The stability evaluation of two types of plug was carried out by investigating the distribution of the factor of safety in the plugs and the distribution of contact pressure over the contact surface. The analysis result shows that the taper-shaped plug is more structurally stable than the wedge-shaped plug for the given geological condition. Possible separation of the rock-concrete interface around the spring line of the wedge-shaped plug is anticipated, which means the possible leakage of compressed air through the side wall and also means the poor mobilization of frictional resistance on that area.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제25권8호
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• pp.432-437
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• 2013

The increase of greenhouse gas emission and decrease of fossil fuel are being caused by the indiscreet consumption of energy by people. Recently, green policy has been globally implemented to reduce energy consumption. This paper studied the research to reduce the energy consumption in buildings, by using the heat storage properties of PCM. PCM has to prevent leakage from the liquid state. Therefore, we prepared form stable PCM, by using the vacuum impregnation method. Three kinds of organic PCMs were impregnated into the structure of porous material. The characteristics of the composites were determined by using SEM, DSC, FTIR and TGA. SEM morphology showed the micro structure of silica fume/PCM. Also, thermal properties were examined by DSC and TGA analyses; and the chemical bonding of the composite was determined by FTIR analysis.

• Journal of the Society of Naval Architects of Korea
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• 제58권1호
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• pp.17-23
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• 2021

The membrane-type Liquefied Natural Gas (LNG) cargo tank is equipped with a double barrier to seal the LNG, of which the secondary barrier serves to prevent LNG leakage and mainly uses fiber-reinforced composite materials. However, the composite materials have thermal expansion anisotropy, which deteriorates shape distortion and mechanical performance due to repeated thermal loads caused by temperature changes between cryogenic and ambient during the unloading of LNG. Therefore, in this study, the longitudinal thermal expansion characteristics of the composite materials were obtained using a vertical thermo-mechanical analyzer, and the elastic modulus was obtained through the tensile test for each temperature to perform thermal load analysis for each direction. This is considered that it is useful to secure reliability from the viewpoint of the design of materials for a LNG cargo hold.

• Journal of Microbiology and Biotechnology
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• 제31권6호
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• pp.890-901
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• 2021

The 11α-hydroxylation of canrenone can be catalyzed by Aspergillus ochraceus in bioreactors, where the geometry of the impeller greatly influences the biotransformation. In this study, the effects of the blade number and impeller diameter of a Rushton turbine on the 11α-hydroxylation of canrenone were considered. The results of fermentation experiments using a 50 mm four-blade impeller showed that 3.40% and 11.43% increases in the conversion ratio were achieved by increasing the blade number and impeller diameter, respectively. However, with an impeller diameter of 60 mm, the conversion ratio with a six-blade impeller was 14.42% lower than that with a four-blade impeller. Data from cold model experiments with a large-diameter six-blade impeller indicated that the serious leakage of inclusions and a 22.08% enzyme activity retention led to a low conversion ratio. Numerical simulations suggested that there was good gas distribution and high fluid flow velocity when the fluid was stirred by large-diameter impellers, resulting in a high dissolved oxygen content and good bulk circulation, which positively affected hyphal growth and metabolism. However, a large-diameter six-blade impeller created overly high shear compared to a large-diameter four-blade impeller, thereby decreasing the conversion ratio. The average shear rates of the former and latter cases were 43.25 s^-1 and 35.31 s^-1, respectively. We therefore concluded that appropriate shear should be applied in the 11α-hydroxylation of canrenone. Overall, this study provides basic data for the scaled-up production of 11α-hydroxycanrenone.

• Geomechanics and Engineering
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• 제17권5호
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• pp.485-496
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• 2019

Sealing of leakage in waterfront or water-retaining structures is one of the major issues in geotechnical engineering practices. With demands for biological methods as sustainable ground improvement techniques, bioclogging, defined as the reduction in hydraulic conductivity of soils caused by microbial activities, has been considered as an alternative to the chemical grout techniques for its economic advantages and eco-friendliness of microbial by-products. This study investigated the feasibility of bioaugmentation and biostimulation methods to induce fermentation-based bioclogging effect in coarse sands. In the bioaugmentation experiments, effects of various parameters and conditions, including grain size, pH, and biogenic gas generation, on hydraulic conductivity reduction were examined through a series of column experiments while Leuconostoc mesenteroides, which produce an insoluble biopolymer called dextran, was used as the model bacteria. The column test results demonstrate that the accumulation of bacterial biopolymer can readily reduce the hydraulic conductivity by three-to-four orders of magnitudes or by 99.9-99.99% in well-controlled environments. In the biostimulation experiments, two inoculums of indigenous soil bacteria sampled from waterfront embankments were prepared and their bioclogging efficiency was examined. With one inoculum containing species capable of fermentation and biopolymer production, the hydraulic conductivity reduction by two orders of magnitude was achieved, however, no clogging was found with the other inoculum. This implies that presence of indigenous species capable of biopolymer production and their population, if any, play a key role in causing bioclogging, because of competition with other indigenous bacteria. The presented results provide fundamental insights into the bacterial biopolymer formation mechanism, its effect on soil permeability, and potential of engineering bacterial clogging in subsurface.

• Plant Journal
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• 제17권2호
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• pp.32-41
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• 2021

Recently, air environmental issues such as fine dust have rapidly emerged as national issues, and intensive environmental regulations are being applied to coal-fired power plants. This study introduces the case of improving the performance of desulfurization facilities for removing sulfur oxides and dust, which are the main air pollutant emitters of coal-fired power plants, and conducted four case studies to improve the performance of 1,000 MW power plants currently in operation and carried out construction. Liquid ratio was increased by remodeling the absorption tower of desulfurization facilities, and vaporization reaction was promoted by increasing the flow rate of oxidized air. In addition, the gas heater leakage rate was improved to improve the efficiency of final desulfurization facilities. It is expected that performance improvement work considering harmony with existing facilities will satisfy the regulations(25ppm of sulfur oxides, 5mg/Sm³) that will be applied from 2023, and can be referred to other thermal power plants for review and application.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제26권11호
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• pp.1644-1652
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• 2022

In the case of safety training where practical training is impossible due to risk problems, training contents using realistic media such as virtual reality or augmented reality are becoming a new alternative. In this paper, we propose a smoke modeling method that can be applied to safety-training contents implemented with realistic media technology. When an accident occurs in a hazardous area such as a petrochemical plant, visibility is not secured due to gas leakage and fire. In order to create such a situation, it is important to realistically express smoke. The proposed method is a smoke model implementation technique that can be effectively applied to the background of complex passages and devices such as petrochemical plants. In the proposed method, the smoke is expressed using volumetric rendering in the post-processing stage for the resulting image of scene rendering. Implementation results in the background of the factory show that the proposed method produces models that can express the smoke realistically.

• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.390-397
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• 2022

The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.

• Journal of the Korean Society of Industry Convergence
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• 제26권3호
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• pp.499-507
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• 2023

The core of the liquefied natural gas (LNG) carrier cargo containment system (CCS) is to store and transport LNG safely under temperatures below -163 degrees Celsius. The secondary barrier of the LNG CCS is adopted to prevent LNG leakage from CCS to the ship's hull structure. Recently, as the size of the LNG CCS increases, various studies have been conducted on the applied temperature and load ranges. The present study investigates the working condition-dependent bonding strength of the PU15 adhesives of the secondary barrier. In addition, the mechanical performance is analyzed at a cryogenic temperature of -170 degrees Celsius, and the failure surface and failure mode are investigated depending on the working condition of the bonded process. Even though the RSB and FSB-based fracture mode was confirmed, the results showed that all the tested scenarios satisfied the minimum requirement of the regulation.